Distribution of country of origin in studies used in Cochrane Reviews.

Inclusion in systematic reviews is one important component in
judging the potential impact of clinical studies upon practice and
hence the 'value for money' of spending for clinical research. This
study aims to quantify the distribution of countries of origin of
clinical studies used in Cochrane Reviews (CRs), and to link these
data to the size of a country and to its spending on research.
Random sample of publications used for CRs published in Issue 1
2008 and of publications used in CRs in the field of complementary
and alternative medicine (CAM). Publications without original data
were excluded. Likely countries of origin determined based on
abstracts/full texts. CIA World Factbook (population data) and OECD
database (economic data) were used. 1,000 random entries out of
140,005 references available in all specialities. In 876 (91.4%) of
959 eligible studies, country of origin was determined. The USA was
the leading contributor (36.0% of the studies), followed by UK
(13.4%), Canada (5.3%), Australia and Sweden (3.7%). In the CAM
sample, country of origin was determined in 458 (93.5%) of 497
assessed studies. Again, the USA was the leading contributor
(24.9%), with China also emerging as a significant contributor
(24.7%) in this field. For both samples, the contribution of
smaller countries (especially Scandinavian countries, Greece, and
Ireland) became more noteworthy when considered in relation to
population size and research spending. Our results support the
leading roles of both the USA and the UK in publishing clinical
papers. The emerging role of China can be seen, particularly
related to CAM studies. Taking into account size of population and
economic power, countries like France, Germany, Italy, and Spain
provide small contributions. In contrast, smaller countries like
Australia, Denmark, Finland, Ireland, New Zealand, and Sweden also
play major roles.